This application proposes a 5-year, multisite prevention outcome study that targets parenting practices in early childhood to reduce risk for a developmental trajectory leading to early-onset substance use and abuse. The family-centered intervention is designed for implementation within the service delivery system of Women, Infants, and Children (WIC) programs. The intervention is tailored to engage high-risk families and to maximize the public health impact on risk for early-onset drug use and related risk. The three WIC sites include an urban, suburban, and rural setting, each containing 240 families (N = 720). Families will be assigned randomly to WIC, as usual, and a family-enhanced WIC service that provides direct support for parenting practices from ages 2 through 7. Children will be followed from age 2 to 7 to evaluate the impact on the family service on school entry adjustment and the emergence of behavior problems at home and school, all precursors to onset use and substance abuse. In addition, we propose support to follow a pilot sample of 120 high-risk families with toddlers, initiated in the fall of 2000 in Pittsburgh, to age 6. Analyses of the impact of implementation will rely on mixture-modeling strategies, to better understand for whom the intervention was most effective. In addition, analyses of the systemic dynamics of WIC, intervention dosage, and the fidelity of the intervention will be associated with reduction of risk for early behavior problems and risk for early-onset substance use. Finally, the intervention, assessment and evaluation procedures will be refined to promote relevance and diffusion of the family-centered intervention to WIC sites across the nation.